The present invention relates to a secondary electron multiplier of the type which employs discrete dynodes, and to a method of producing such a secondary electron multiplier.
Such a secondary electron multiplier is known from inhouse publication SC-5 by Hamamatsu (1983 catalog) where it appears under the nomenclature R 1635. This device has eight stages and a diameter of 10 mm as well as a length of about 45 mm. These dimensions do not permit its use in miniaturized measuring systems.
Also known are micro-channel plates (see for example Joseph Ladislas Wiza, "Microchannel Plate Detectors," Nuclear Instruments and Methods 162, (1979) pages 587-601). Although micro-channel plates meet the requirement of compact size, they have a considerable dead time after a signal pulse so that their usability for very weak radiation and particle signals remains limited.
Also known are layered channel plates (see V. Jares et al, "A Flat Channel System for Imaging Purposes," Advances in Electronics and Electron Physics 33A, (1972), pages 117-123). Although layered channel plates avoid the drawback of long dead times, they exhibit considerable electron losses from stage to stage so that they again are unsuitable for use with extremely low radiation or particle signals. In other known layered channel plates (U.S. Pat. No. 4,482,836) such losses are reduced by shaping the channel walls by means of etching. But this type of shaping can be done only within narrow limits. Finally, arrays of secondary electron multipliers are known from high-energy physics (see F. Binon et al, "Hodoscope Multiphoton Spectrometer GAMS-2000," Nuclear Instruments and Methods in Physics Research, A248 (1986), pages 86-102). The great space requirement of such devices makes them entirely unsuitable for the construction of miniaturized measuring systems.